It looks like your gun has a plastic ramp sight, that would place it with the vary oldest of PGs, Your gun came from the factory as a bolt action gun and was probably sent back or taken to a good Sheridan dealer for the pump upgrade. As stated above it was modified several other times as well. The CA (constant air) adapter is designed for Thermo valved tanks and pre-dates the Tippmann ASA.
Originally Posted by Tescrash
Almost only counts in horseshoes in handgrenades....